4β-1″-[(2″-substituted benzoyl) anilino]podophyllotoxin analogues useful as anticancer agents

ABSTRACT

The present invention provides a new class of compounds 4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin exhibiting anti cancer activity and a process for preparing the same.

TECHNICAL FIELD

The present invention relates to a process for the synthesis of new4β-1″-[2″-(substituted benzoyl)anilino]podophyllotoxin analogues areuseful anticancer agents. The present invention particularly relates tothe synthesis of new class of 4β-O-benzoyl anilino congeners of thepodophyllotoxin as useful anticancer agents.

BACKGROUND ART

Etoposide and teniposide two synthetic podophyllotoxin derivatives whichare important drugs that currently being used in the treatment of smalllung cancer, testicular carcinoma, lymphoma, Kaposi's sarcoma. Theclinical efficacy and intriguing mechanism of etoposide has greatlystimulated interest in further studies on the modification of the C-4substution of this compound and for better antitumour activity (Jadine,I. In Anticancer Agents Based on Natural Products Models; Cassady, J.M., Dours, J., Eds.; Academic press: New York, 1980, p 319.; Levy, R.K.; Hall, I. H.; Lee, K. H. J. Pharm. Sci. 1983,72,1158.; Issell, B. F.;Muggia, F. M.; Carter, S. K. Etoposide [VP-16]Current Status and NewDevelopments; Academic Press New York, 1984.; Stio, H.; Yoshikawa, H.;Nishimura, Y.; Kondo, S.; Takeuchi, T.; Umezawa, H. Chem. Pharm. Bull.1986,34,3733. Satio, H.; Nishimura, Y.; Kondo, S.; Komuro, K.; Takeuchi,T.; Bull. Chem. Soc. Jpn.1988, 61, 2493). It has been well establishedthat the principal mechanism of the action for etoposide is by theinhibition of catalytic activity of DNA topoisomarase II and concurrentenzyme mediated production of lethal DNA strand breaks. Structureactivity relationship studies for the podophyllotoxin-derived compoundshave shown the trans C/D ring juncture is a essential for the antitumouractivity. A number of studies have been carried out on the structuralmodification of glycoside moiety by 4-alkylamino or 4-arylaminosubstituents have improved the inhibitory activity on human DNAtopoisomarase II as well as stronger activity in causing cellularprotein length DNA breakage (Lee. K. H.: Imakura. Y.: Haruna. M.; Beers,S. A.; Thurston, L. S.; Dai, H. J.; Chen, C. H.; Liu, S. Y.; Cheng, Y.C. J. Nat. Prod. 1989, 52, 606. Liu, S. Y.; Hawang, B. D.; Haruna, M.;Imakura, Y.; Lee, K. H.; Cheng, Y. C. Mol. Pharmcol. 1989, 36, 78. Lee,K, H.; Beers, S. A.; Mori, M.; Wang, Z. Q.; Kuo, Y. H.; Li, L.; Liu, S.Y.; cheng, Y. C.; J. Med. Chem. 1990, 33,1364). In the context a largenumber of 4β-aryl amino derivatives of 4′-O-demethyl epipodophyllotoxinbased compound have been synthesized and investigated for theirantitumour activity.

OBJECTIVES OF THE INVENTION

The main object of the invention is to provide the new4β-[2″-benzoylsubstituted] arylamino podophyllotoxin analogues useful asanticancer agents.

Another object of the present invention is to provide a process for thesynthesis of new 4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxinderivatives as useful anticancer agents, which obviates the draw backsas detailed above.

Another object of the present invention is to provide new andstereo-selective compounds of the podophyllotoxins and4′-O-demethylepipodophyllotoxin in good yields.

Still another object of the present invention is to provide the key stepfor the synthesis of these analogues by direct nucleophilic substitutionof the C-4β-bromo intermediate.

SUMMARY OF THE INVENTION

The above and other objective of the present invention are achieved byproviding the new class of C₄-β-aryl substituted and N-linkedderivatives of podophyllotoxin and 4′-O-demethylepipodophyllotoxin,which have been synthesized as anti cancer agents.

Accordingly, the present invention provides new class of4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin analogues havingthe structural formula (2).

The present invention also provides a process for the preparation of new4β-1″-[2″-(substituted benzoyl)anilino] podophyllotoxin analogues asuseful anticancer agents. More particularly, it provides a process forthe preparation of 4β-1″-[2″-(substituted benzoyl)anilino] derivativesof podophyllotoxin.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 represents structure of podophyllotoxin, Etoposide andTeniposide.

FIG. 2 represents general formula of compounds of the class4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin analogues.

FIG. 3 discloses the process for the synthesis of new podophyllotoxinanalogues as anticancer agents producing the novel and stereo-selectivederivatives of the podophylotoxin in good yields.

DETAILED DESCRIPTION

The process for the synthesis of new podophyllotoxin analogues asanticancer agents produces the novel and stereo-selective derivatives ofthe podophyllotoxin in good yields, where in the key step for thesynthesis of these analogues is by direct nucleophilic substitution ofC-4β-bromo intermediates, 4β-bromo-podophyllotoxin and4′-O-demethylepipodophyllotoxin, which have been reacted withsubstituted or unsubstituted 2-aminobenzophenones in a stereo-selectivemanner to afford the 4β-1″-[{2″-benzoyl substituted}anilino]podophyllotoxin derivatives.

These 4-bromopodophyllotoxin intermediates have been prepared by thebromination of the related podophyllotoxin compounds as described in theliterature [Kuhn, M.; Keller-Juslen, C.; Van Wartburg, Helv. Chemica.Acta, 1969, 52, 944].

In an embodiment of the present invention, the naturally occurringpodophyllotoxin lignan was isolated from Podophyllum peltatum linnaeus.

In another embodiment of the present invention the synthesis of4β-intermediates have been carried out from bromination ofpodophyllotoxin and 4′-O-demethylepipodophyllotoxin.

In yet another embodiment of the present invention 1–2 eq. of differentunsubstituted and substituted benzophenone compounds have been used.

In still another embodiment of the present invention a variety ofsolvents were used for the nucleophilic substitution step, such asdichloromethane, chloroform and tetrahydrofuran.

In still yet another embodiment of the present invention catalyticamount of BU₄N⁺I⁻ (0.2–0.5eq) was used by stirring the reaction mixturebetween −10° C. to room temperature for 2 to 10 h.

In still another embodiment of the present invention bases like K₂CO₃,Et₃N were also used.

In still another embodiment of the present invention the purification ofthese analogues was done by column chromatography employingchloroform/methanol as eluent.

Thus, the present invention provides new classes of podophyllotoxinanalogues, which were synthesized in a stereo selective manner.

A program was initiated in the laboratory for the design and synthesisof new 4β-aryl amino substituted podophyllotoxin congeners with enhancedantitumour activity and/or activity against etoposide resistant tumorcell lines. In these efforts new 4β-1″-[{2″-benzoyl substituted}anilino]podophyllotoxin derivatives have been synthesized and evaluated fortheir cytotoxicity and anticancer potency. Interestingly, some of thecompounds have shown greater in vitro cytotoxicity values compared toetoposide. The synthesis of these compounds has been carried out asdescribed in the scheme using podophyllotoxin obtained from the resin.The cytotoxicity of 4 a–4 p values have been illustrated in the Table 1.

TABLE 1 Cytotoxicity (in vitro) data for some representative compounds.

S. No. R R₁ R₂ GI₅₀ μM 4a CH₃ H H 0.04–0.5  4b H H H  15–382 4c CH₃ 2-Cl4-Cl 0.059–0.876 4d H 2-Cl 4-Cl  0.1–0.24 4e CH₃ H 4-NO₂ <10 nM–0.28  4f H H 4-NO₂ 0.01–0.24 4g CH₃ H 4-Cl 0.07–1.1  4h H H 4-Cl  14–270 4iCH₃ 2-F 4-Cl 0.14–0.3  4j H 2-F 4-Cl 0.004–0.1  4k CH₃ H H 0.1–1   4l HH H  2–16 4m CH₃ H 4-NO₂ 0.01–0.2  4n H H 4-NO₂ 0.01–0.24 4o CH₃ H 4-NH₂0.04–1   4p H H 4-NH₂ 0.015–0.4 

Some of the compounds of the present invention are given below:

-   a) 4β-1″-[2″-(Benzoyl)anilino]-4-desoxypodophyllotoxin-   b) 4′-O-Demethyl-4β-1″-[2″-(benzoyl)anilino]-4-desoxypodophyllotoxin-   c)    4β-1″-[2″-(2-Chlorobenzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin-   d)    4′-O-1″-[2″-(2-Chlorobenzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin-   e) 4β-1″-[2″-(Benzoyl)-4″-nitroanilino]-4-desoxypodophyllotoxin-   f)    4′-O-Demethyl-4β-1″-[2″-(Benzoyl)]-4″-nitroanilino]-4-desoxypodophyllotoxin-   g) 4β-1″-[2″-(Benzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin-   h)    4′-O-Demethyl-4β-1″-[2″-(Benzoyl)]-4″-chloroanilino]-4-desoxypodophyllotoxin-   i)    4β-1″-[2″-(2-Fluorobenzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin-   j)    4′-O-Demethyl-4β-1″-[2″-(2-Fluorobenzoyl)-4″-chloroanilino]-4-desoxypodophylltoxin-   k) 4β-1″-[3″-(Benzoyl)anilino]-4-desoxypodophyllotoxin-   l) 4′-O-Demethyl-4β-1″-[3″-(benzoyl)anilino]-4-desoxypodophyllotoxin-   m) 4β-1″-[2″-(Benzoyl)-2 ″-nitroanilino]-4-desoxypodophyllotoxin-   n)    4′-O-Demethyl-4β-1″-[4″-(Benzoyl)]-2″-nitroanilino]-4-desoxypodophyllotoxin.

The following examples are given by way of illustration and should notbe construed the limit and the scope of the invention.

Experimental

EXAMPLE 1

4β-1″-[2″-(Benzoyl)anilino]-4-desoxypodophyllotoxin (4a):—4β-Bromo-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol) was reacted with2-aminobenzophenone (0.045 g, 0.23 mmol) in presence of Et₃N (0.032 g,0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in dry tetrahydrofuran atroom temperature for 4 h. After completion of reaction solvent wasremoved in vacuo. The residue was subjected to silica gel columnchromatography using chloroform-methanol (9.8:0.2) as eluent.

Yield 60%, mp 140° C.; [α]²⁵ _(D) −112 (c, 0.1 CHCl₃) ¹H NMR (200 MHz,CDCl₃): δ 8.82 (d, 1H), 7.50 (m, 7H), 6.80 (s, 1H), 6.75 (d, 1H), 6.68(d, 1H), 6.55 (s, 1H), 6.35 (s, 2H), 5.96 (d, 2H), 5.38 (s, 1H), 4.92(m, 1H), 4.65 (d, 1H), 4.35 (t, 1H), 3.96 (t, 1H), 3.82 (d, 9H), 3.20(q, 1H), 3.50 (m, 1H) MS (m/e) 593 (M⁺, 40%), 576, 467, 397, 282, 229,185. IR (KBr) cm⁻¹: 3400 (N—H), 2900 (aliphatic C—H), 1780 (lactone),1650 (ketone), 1500, 1480, 1410, 1300, 1250 (aromatic C═C).

EXAMPLE 2

4′-O-Demethyl-4β-1″-[2″-(benzoyl)anilino]-4-desoxypodophyllotoxin (4b):—4β-Bromo-4′-O-demethyl-4-desoxypodophyllotixin (0.1 g, 0.21 mmol)was reacted with 2-aminobenzophenone (0.045 g, 0.23 mmol) in presence ofEt₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in drytetrahydrofuran at room temperature for 4 h. After the completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.8:0.2) aseluent.

Yield 50% m.p 154–156° C.; [α]²⁵ _(D) 111 (c, 1.1, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 8.85 (d, 1H), 7.50 (m, 7H), 6.80 (s, 1H), 6.75 (d, 1H),6.68 (d, 1H), 6.55 (s, 1H), 6.35 (s, 2H), 5.96 (d, 2H), 5.38 (s, 1H),4.92 (m, 1H), 4.65 (d, 1H), 4.35 (t, 1H), 3.96 (t, 1H), 3.82 (s, 6H),3.20 (q, 1H), 3.05 (m, 1H) MS (m/e) 579(M⁺, 25%), 495, 467, 397, 229,185. IR (KBr) cm⁻¹: 3550 (O—H), 3400(N—H) 2900 (aliphatic C—H), 1750(lactone), 1650 (ketone), 1500, 1480, 1410, 1300, 1250 (aromatic C═C).

EXAMPLE 3

4β-1″-[2″-(2-Chlorobenzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin (4c):—4β-bromo-4-desoxypodophyllotoxin (0.10 g 0.21 mmol) was reacted with2-amino-2′, 5′-dichlorobenzophenone (0.06 g, 0.23 mmol) in presence ofEt₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g 0.042 mmol) in drytetrahydrofiuran at room temperature for 5 h. After the completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.7:0.3) aseluent.

Yield 64% m.p 142–145° C.; [α]²⁵ _(D) −84 (c, 0.87, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.10 (d, 1H), 7.40 (m, 5H), 7.20 (d, 1H), 6.78 (s, 1H),6.75 (d, 1H), 6.52 (s, 1H), 6.35 (s, 2H), 5.96 (d, 2H), 4.97 (m, 1H),4.65 (d, 1H), 4.35 (t, 1H), 3.90 (t, 1H), 3.77 (d, 9H), 3.20 (q, 1H),3.10 (m, 1H) MS (m/e) 663 (M⁺, 20%), 662, 661, 460, 387, 289. IR (KBr)cm⁻¹: 3350 (N—H), 2900 (aliphatic C—H), 1760 (lactone), 1640 (ketone),1550, 1480, 1250 (aromatic C═C).

EXAMPLE 4

4′-O-Demethyl-4β-1″-[2″-(2-Chlorobenzoyl)-4″-chloroanilino]-4-desoxypodo-phyllotoxin(4 d):—4β-Bromo-4′-O-Demethyl-4-desoxypodophyllotoxin (0.10 g 0.21 mmol)was reacted with 2-amino-2′, 5′-dichlorobenzophenone (0.06 g, 0.23 mmol)in presence of Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g 0.042mmol) in tetrahydrofuran at room temperature for 5 h. After thecompletion of reaction solvent was removed in vacuo. The residue wassubjected to silica gel column chromatography using chloroform-methanol(9.7:0.3) as eluent.

Yield 70% m.p 151–153° C.; [α]²⁵ _(D) −91 (c, 0.93., CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.10 (d, 1H), 7.40 (m, 5H), 6.77 (s, 1H), 6.70 (d, 1H),6.30 (s, 1H), 5.96 (d, 2H), 5.40 (s, 2H), 4.90 (m, 1H), 4.65 (d, 1H),4.30 (t, 1H), 4.10 (t, 1H), 3.80 (s, 6H), 3.20 (q, 1H), 3.10 (m, 1H). MS(m/e) 649 (M⁺, 20%), 648, 647, 446, 383, 289. IR (KBr) cm⁻¹: 3320 (N—H),2900 (aliphatic C—H), 1760 (lactone), 1650 (ketone), 1550, 1480, 1410,1250 (aromatic C═C).

EXAMPLE 5

4β-1″-[2″-(Benzoyl)-4″-nitroanilino]-4-desocypodophyllotocin (4e):—4β-Bromo-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol) was reacted with2-amino-5-nitro-benzophenone (0.056 g, 0.23 mmol) in presence of Et₃N(0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in drytetrahydrofuran at room temperature for 8 h. After completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.5:0.5) aseluent.

Yield 40%, mp 163–167° C.; [α]²⁵ _(D) −85 (c, 1.2, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.50 (d, 1H), 8.57 (d, 1H), 8.32 (q, 1H), 7.60 (m, 4H),6.75 d, 1H), 6.75 (s, 1H) 6.60 (d, 1H), 6.40 (d, 1H), 6.30 (s, 2H), 6.00(d, 2H), 5.05 (m, 1H), 4.70 (d, 1H), 4.40 (t, 1H), 3.90 (t, 1H) 3.80 (d,9H), 3.15 (d, 1H), 2.95 (m, 1H) MS (m/e) 638 (M⁺, 10%), 582, 496, 439,411, 383, 289. IR (KBr) cm⁻¹: 3450 (N—H), 2950 (aliphatic C—H), 1740(lactone), 1650 (ketone), 1550, 1480, 1250 (aromatic C═C).

EXAMPLE 6

4′-O-Demethyl-4β-1″-[2″-(Benzoyl)]-4″-nitroanilino]-4-desoxypodophyllotoxin(4 f):—4β-Bromo-4′-O-demethyl-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol)was reacted with 2-amino-5-nitro-benzophenone (0.056 g, 0.23 mmol) inpresence of Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.15 g, 0.042 mmol)in dry tetrahydrofuran at room temperature for 8 h. After completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.5:0.5) aseluent.

Yield 38%, mp 169–171° C.; [α]²⁵ _(D) −89 (c, 1.0, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.47 (d, 1H), 8.55 (d, 1H), 8.30 (q, 1H), 7.60 (m, 4H),6.80 (d, 1H), 6.55 (s, 1H) 6.35 (d, 1H), 6.30 (s, 2H), 6.00 (d, 2H),5.87 (s, 1H), 5.00 (m, 1H), 4.65 (d, 1H), 4.30 (m, 2H), 3.80 (d, 6H),3.15 (d, 1H), 2.00 (m, 1H) MS (m/e) 624(M⁺, 15%), 568, 401, 383,289,229, 185. IR (KBr) cm ⁻¹: 3560 (O—H), 3400 (N—H) 2900 (aliphatic C—H),1740 (lactone), 1650 (ketone), 1500, 1480, 1250 (aromatic C═C).

EXAMPLE 7

4β-1″-[2″-(Benzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin (4g):—4β-bromo-4-desoxypodophyllotoxin (0.10 g 0.21 mmol) was reacted with2-amino-5-chlorobenzophenone (0.053 g, 0.23 mmol) in presence of Et₃N(0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g 0.042 mmol) in at roomtetrahydrofuran temperature for 6 h. After the completion of reactionsolvent was removed in vacuo. The residue was subjected to silica gelcolumn chromatography using chloroform-methanol (9.7:0.3) as eluent.

Yield 56% m.p 139–142° C.; [α]²⁵ _(D) −103 (c, 0.93, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 8.72 (d, 1H), 7.60 (m, 7H), 7.45 (q, 1H), 6.80 (s, 1H),6.75 (d, 1H), 6.55 (s, 1H), 6.35 (s, 2H), 5.98 (d, 2H), 4.95 (m, 1H),4.65 (d, 1H), 4.40 (t, 1H), 3.95 (t, 1H), 3.80 (d, 9H), 3.20 (q, 1H),3.10 (m, 1H) MS (m/e) 628 (M⁺, 20%), 627, 441, 383, 289, 229, 185 IR(KBr) cm⁻¹: 3350 (N—H), 2900 (aliphatic C—H), 1780 (lactone), 1660(ketone), 1500, 1480, 1410, 1250 (aromatic C═C).

EXAMPLE 8

4′-O-Demethyl-4β-1″-[2″-(Benzoyl)]-4″-chloroanilino]-4-desoxypodophyllotoxin(4 h):—4β-Bromo-4′-O-demethyl-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol)was reacted with 2-amino-5-chlorobenzophenone (0.053 g, 0.23 mmol) inpresence of Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol)in dry tetrahydrofuran at room temperature for 6 h. After completion ofthe reaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.7:0.3) aseluent.

Yield 50%, mp 146–149° C.; [α]²⁵ _(D) −105 (c, 0.97, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 8.68 (d, 1H), 7.52 (m, 7H), 7.35 (q, 1H), 6.72 (s, 1H),6.65 (d, 1H), 6.50 (s, 1H) 6.30 (s, 2H), 5.96 (d, 2H), 5.35 (s, 1H),4.85 (m, 1H), 4.60 (d, 1H), 4.30 (t, 1H), 3.85 (d, 1H), 3.80 (s, 6H),3.10 (q, 1H), 3.00 (m, 1H) MS (m/e) 614 (M⁺, 10%), 613, 401, 383, 289,229, 185 IR (KBr) cm⁻¹: 3500 (O—H), 3360 (N—H) 2900 (aliphatic C—H),1750 (lactone), 1640 (ketone), 1500, 1480, 1230 (aromatic C═C).

EXAMPLE 9

4β-1″-[2″-(2-Fluorobenzoyl)-4″-chloroanilino]-4-desoxypodophyllotoxin (4i):—4β-bromo-4-desoxypodophyllotoxin (0.10 g 0.21 mmol) was reacted with2-amino-5-chloro-2′-fluorobenzophenone (0.057 g, 0.23 mmol) in presenceof Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g 0.042 mmol) in drytetrahydrofuran at room temperature for 5 h. After the completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.7:0.3) aseluent.

Yield 68% m.p 123–128° C.; [α]²⁵ _(D) −89 (c, 1.0, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.10 (d, 1H), 7.45 (m, 6H), 6.80 (s, 1H), 6.75 (d, 1H),6.55 (s, 1H), 6.35 (s, 2H), 6.00 (d, 2H), 4.95. (m, 1H), 4.70 (d, 1H),4.40 (t, 1H), 3.95 (t, 1H), 3.82 (d,9H), 3.10(m,1H) MS (m/e) 646 (M⁺,30%), 645, 631, 411, 397, 229, 185 IR (KBr) cm⁻¹: 3400 (N—H), 2950(aliphatic C—H), 1760 (lactone), 1650 (ketone), 1500, 1480, 1300, 1250(aromatic C═C).

EXAMPLE 10

4′-O-Demethyl-4β-1″-[2″-(2-Fluorobenzoyl)-4″-chloroanilino]-4-desoxypodo-phyllotoxin(4 j):—4β-Bromo-4′-O-Demethyl-4-desoxypodophyllotoxin (0.10 g 0.21 mmol)was reacted with 2-amino-5-chloro-2-fluorobenzophenone (0.057 g, 0.23mmol) in presence of Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g0.042 mmol) in dry tetrahydrofuran at room temperature for 5 h. Afterthe completion of reaction solvent was removed in vacuo. The residue wassubjected to silica gel column chromatography using chloroform-methanol(9.7:0.3) as eluent.

Yield 60% m.p 164–167° C.; [α]²⁵ _(D) −85 (c, 1.01, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 9.05 (d, 1H), 7.48 (m, 6H), 6.80 (s, 1H), 6.75 (d, 1H),6.52 (s, 1H C-8), 6.35 (s, H), 6.00 (d, 2H), 5.10 (s, 1H), 4.98 (m, 1H),4.70 (t, 1H), 4.40 (t, 1H), 3.95 (t, 1H), 3.82 (s, 6H), 3.20 (q, 1H),3.10 (m, 1H). MS (m/e) 632 (M⁺, 25%), 631, 401, 383, 229, 185 IR (KBr)cm⁻¹: 3520 (O—H), 3440(N—H), 2900 (aliphatic C—H), 1750 (lactone), 1650(ketone), 1500, 1480, 1300, 1250 (aromatic C═C).

EXAMPLE 11

4β-1″-[3″-(Benzoyl)anilino]-4-desoxypodophyllotoxin (4k):—4β-Bromo-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol) was reacted with2-amino-4-bromobenzo-phenone (0.064 g, 0.23 mmol) in presence of Et₃N(0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in drytetrahydrofuran at room temperature for 3 h. After completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.8:0.2) aseluent.

Yield 61%, mp 141–144° C.; [α]²⁵ _(D) −102 (c, 1.1, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 7.80 (d, 1H), 7.50 (m, 3H), 7.25 (d, 1H), 7.10 (d, 1H),7.01(s, 1H), 6.80 (s, 1H), 6.75 (d, 1H), 6.50 (s, 1H), 6.28 (s, 2H),5.95 (d, 2H), 5.30 (s, 1H), 4.75 (m, 1H), 4.55 (d, 1H), 4.40 (t, 1H),4.00 (t, 1H) 3.75 (q, 9H), 3.05 (m, 2H) MS (m/e) 593 (M⁺25%), 576, 467,397, 229, 185. IR (KBr) cm⁻¹: 3400 (N—H), 2950 (aliphatic C—H), 1760(lactone), 1650 (ketone), 1500, 1480, 1250 (aromatic C═C).

EXAMPLE 12

4′-O-Demethyl-4β-1″-[3″-(benzoyl)anilino]-4-desoxypodophyllotoxin (4l):—4β-Bromo-4′-O-demethyl-4-desoxypodophyllotixin (0.1 g, 0.21 mmol)was reacted with 3-aminobenzophenone (0.045 g, 0.23) in presence of Et₃N(0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in drytetrahydrofuran at room temperature for 3 h. After the completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.8:0.2) aseluent.

Yield 63% m.p 151–154° C.; [α]²⁵ _(D) −102; (c, 1.1. CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 7.84 (d, 2H), 7.52 (m, 3H), 7.25 (d, 1H), 7.10 (d, 1H),7.01(s, 1H), 6.90 (s, 1H), 6.78 (d, 1H), 6.54 (s, 1H), 5.95 (d, 2H),4.75 (m, 1H), 4.55 (d, 1H), 4.40 (t, 1H), 4.00 (t, 1H), 3.75 (d, 9H),3.05 (m, 2H) MS (m/e) 579 (M⁺, 25%) 382, 283, 229, 185. IR (KBr) cm⁻¹:3520 (O—H), 3390 (N—H) 2900 (aliphatic C—H), 1760 (lactone), 1650(ketone), 1500, 1480, 1250 (aromatic C═C).

EXAMPLE 13

4β-1″-[2″-(Benzoyl)-2″-nitroanilino]-4-desoxypodophyllotoxin (4m):—4β-Bromo-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol) was reacted with4-amino-3-nitro-benzophenone (0.056 g, 0.23 mmol) in presence of Et₃N(0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol) in drytetrahydrofuran at room temperature for 8 h. After completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.4:0.6) aseluent.

Yield 42%, mp 163–167° C.; [α]²⁵ _(D) −81 (c, 0.9, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 8.68 (d, 1H), 8.50 (d, 1H), 8.05 (d, 1H), 7.75 (d, 2H),7.55 (m, 3H), 6.93 (d, 1H) 6.750 (s, 1H), 6.58 (s, 1H) 6.50 (d, 1H),6.32 (s, 2H), 6.00 (d, 2H), 5.32 (d, 1H), 5.07 (m, 1H), 4.68 (d, 1H),4.35 (t, 1H), 3.92 (t, 1H), 3.80 (d, 9H), 3.13 (d, 1H) MS (m/e) 638 (M⁺,15%), 582, 524, 428, 411, 383, 289. IR (KBr) cm⁻¹: 3400 (N—H), 2950(aliphatic C—H), 1760 (lactone), 1640 (ketone), 1500, 1480, 1410, 1300,1250 (aromatic C═C).

EXAMPLE 14

4′-O-Demethyl-4β-1″-[4″-(Benzoyl)]-2″-nitroanilino]-4-desoxypodophyllotoxin(4 n):—4β-Bromo-4′-O-demethyl-4-desoxypodophyllotoxin (0.1 g, 0.21 mmol)was reacted with 4-amino-3-nitrobenzophenone (0.056 g, 0.23 mmol) inpresence of Et₃N (0.032 g, 0.32 mmol) and Bu₄N⁺I⁻ (0.015 g, 0.042 mmol)in dry tetrahydrofuran at room temperature for 8 h. After completion ofreaction solvent was removed in vacuo. The residue was subjected tosilica gel column chromatography using chloroform-methanol (9.6:0.4) aseluent.

Yield 34%, mp 170–175° C.; [α]²⁵ _(D) −85 (c, 1.0, CHCl₃) ¹H NMR (200MHz, CDCl₃): δ 8.70 (d, 1H), 8.50 (d, 1H), 8.10 (d, 1H), 7.75 (m, 3H),6.93 (d, 1H), 6.72 (s, 1H) 6.58 (s, 1H), 6.32 (s, 2H), 6.00 (d, 2H),5.40 (s, 1H), 5.05 (m, 1H), 4.65 (d, 1H), 4.35 (t, 2H), 3.90 (t, 1H),3.80 (s, 6H), 3.10 (d, 2H) MS (m/e) 624 (M⁺, 15%), 467, 401, 229, 185 IR(KBr) cm⁻¹: 3530 (O—H), 3450 (N—H) 2900 (aliphatic C—H), 1750 (lactone),1650 (Ketone), 1500, 1480, 1410, 1250 (aromatic C═C).

In conclusion, the main advantages of the present inventions are thatthese new 4β-1″-[2″-(substituted benzoyl)anilino] podophylotoxinanalogues have exhibited promising in vitro cytotoxic activity andenhanced potential as anticancer agents. Further, these compounds havebeen prepared 4β-bromopodophylltoxin upon reaction with thecorresponding 2-aminobenzophenone in the presence of Et₃N and BU₄N⁺I⁻ atroom temperature to provide the 4β-1″-[2″-(substituted benzoyl)anilino]podophylotoxin analogues in very good yields and in almoststereoselective manner.

1. Analogs of 4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin ofcompound 2

wherein R, R₁ and R₂ independently or in combination represents R=H orCH₃ R₁=H or halogen R₂=H, NO₂ or halogen.
 2. Analogs of4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin as claimed inclaim 1 selected from the group consisting of: S. No R R₁ R₂ GI₅₀ μM 4aCH₃ H H 0.04–0.5  4b H H H  15–382 4c CH₃ 2-Cl 4-Cl 0.059–0.876 4d H2-Cl 4-Cl  0.1–0.24 4e CH₃ H 4-NO₂ <10 nM–0.28   4f H H 4-NO₂ 0.01–0.244g CH₃ H 4-Cl 0.07–1.1  4h H H 4-Cl  14–270 4I CH₃ 2-F 4-Cl 0.14–0.3  4jH 2-F 4-Cl 0.004–0.1  4k CH₃ H H 0.1–1   4l H H H  2–16 4m CH₃ H 4-NO₂0.01–0.2  4n H H 4-NO₂ 0.01–0.24 4o CH₃ H 4-NH₂ 0.04–1   4p H H 4-NH₂0.015–0.4 .


3. A process for the preparation of 4β-1″-[{2″-benzoylsubstituted}anilino] podophyllotoxin analogs of Compound 2

wherein R, R₁ and R₂ independently or in combination represents R=H orCH₃ R₁=H or halogen R₂=H, NO₂ or halogen the process comprising thefollowing steps: a) reacting 4β-bromo-4-dioxypodophyllotoxin withsubstituted or unsubstituted 2-aminobenzophenone in presence of phasetransfer catalyst, base in an anhydrous organic solvent medium at atemperature ranging between −10° to 40° C. for 4–16 hours, b) removingthe organic solvent from the reaction mixture of step (a) under reducedpressure to obtain a residue, and c) purifying the residue of step (b)over silica gel column, eluting with mixture of chloroform-methanol toobtain the required 4β-1″-[{2″-benzoyl substituted}anilino]podophyllotoxin analogs.
 4. A process as claimed in claim 3 wherein instep (a), the phase transfer catalyst used is selected from a groupconsisting of tetrabutyl ammonium chloride, tetrabutyl ammonium bromide,tetra butyl ammonium iodide or aliquat
 336. 5. A process as claimed inclaim 3 wherein in step (a), the substituted 2-amino benzophenone areselected from group consisting of 2-amino-2′, 5′-dichlorobenzophenone,2-amino-5-nitrobenzophenone, 2-amino-5-chlorobenzophenone,2-amino-5-chlorobenzophenone, 2-amino-5-chloro-2′-fluorobenzophenone,2-amino-4′bromobenzophenone, and 4-amino-3-nitrobenzophenone.
 6. Aprocess as claimed in claim 3 wherein in step (a), the organic solventused is selected from group consisting of dichlorormethane, chloroform,tetrahydrofuran or dioxane.
 7. A process as claimed in claim 3 whereinin step (a), the base used is selected from group consisting oftrimethylamine, triethylamine, sodium carbonate, potassium carbonate,cesium carbonate and barium carbonate.
 8. A process as claimed in claim3 wherein the reaction is carried out at room temperature.
 9. A processas claimed in claim 3 wherein in step (a), the molar ratio ofsubstituted or unsubstituted benzophenone and the bromocompound used isin the range of 1:1 to 2:1 and preferably 1:1.17.
 10. A process asclaimed in claim 3 wherein in step (a), the mole equivalent ratio ofbromo compound to phase transfer catalyst is in the range of 1:0.2 to1:0.5.
 11. A method for treating cancer in a subject in need thereofcomprising administering a pharmaceutically effective dosage of4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxin analogues ofgeneral formula (2) as claimed in claim
 1. 12. A method as claimed inclaim 11 wherein 4β-1″-[{2″-benzoyl substituted}anilino] podophyllotoxinanalogs are used singly or in combination with each other.
 13. A methodas claimed in claim 11 wherein the analogs of general formula (2) areadministered systemically or orally.
 14. A method as claimed in claim 11wherein the subject is a mammal.
 15. A method as claimed in claim 14wherein the subject is a human.
 16. A method as claimed in claim 11,wherein the compound of general formula (2) is administered to thesubject in combination with pharmaceutically acceptable additives,carriers, diluent, solvent, filter, lubricant, excipient, binder orstabilizer.
 17. A method as claimed in claim 11 wherein the GI 50 valueof in vitro anti-cancer activity of preferred analogs is in the range of0.001–382.
 18. A process as claimed in claim 4, wherein the phasetransfer catalyst is tetrabutylammonium iodide.
 19. A process as claimedin claim 7, wherein the organic solvent is tetrahydrofuran.
 20. Aprocess as claimed in claim 8, wherein the base is triethylamine.
 21. Aprocess as claimed in claim 9, wherein the molar ratio is 1:1.17.